Why Do Dogs Love Laying in the Sun?

Vitamin D is essential to human health and is produced by our bodies in response to moderate sun exposure. This powerful vitamin strengthens the immune system, regulates the body's absorption of calcium and phosphorous, and increases serotonin levels.

Humans aren't the only creatures who need vitamin D in their diet — in fact, it may be one of the main reasons why dogs sunbathe. Vitamin D performs the same functions for our canine friends as it does for us and contributes to the health of their bones, muscles, immune systems, and brains.

Dogs can absorb vitamin D through both their skin and their digestive tracts. Dogs' bodies are able to produce vitamin D, but not in the amounts they need, so they must supplement this somehow. (Most commercial dog foods have vitamin D added for this reason). When a dog stretches out in direct sunlight, those warm rays are absorbed by the oils in their skin and converted into vitamin D. Yet, Dogs' fur can prevent them from fully absorbing the vitamin through their skin, so they groom themselves in order to ingest it.

Vitamin D has been shown to boost levels of serotonin in both humans and animals. Serotonin helps to regulate many mental and physical functions, from mood and behavior to appetite and digestion, and an imbalance of it can lead to feeling tired and grumpy. Lower levels of serotonin are thought to be the primary cause for Seasonal Affective Disorder (SAD), a mood disorder that can cause depression. The disorder tends to occur at the same time every year in places where there is less sunlight during certain seasons. It's common in parts of the northern hemisphere, where dreary winters can mean many days in a row without sunshine. It's been theorized that dogs may also experience SAD due to seasonal changes in sunlight, which may manifest as lethargy, extra time spent napping, or irritability.

Luckily, the remedy for SAD dogs is the same as it is for humans, and increasing their sun exposure (or the availability of indoor light) can be a big help to them. Dogs may naturally seek out more sunbathing opportunities during the times of the year when sunlight is limited in order to boost their serotonin levels — so they can feel their best.

In addition to serotonin, sunlight can help regulate levels of the hormone melatonin in dogs. Melatonin plays a key role in a dog's circadian rhythm, which serves as a kind of internal clock that optimizes brain activity and tells their body when it's time to sleep.

A good balance of serotonin, melatonin, and vitamin D is essential for keeping our pups feeling their best. Dogs seeking out patches of sun is likely an instinctual drive to keep themselves happy and healthy.

There's a shorter and simpler component to this adorable phenomenon as well — dogs love laying in the sun because it feels good. Just as you might enjoy drinking your morning coffee outside on a sunny day, sunshine feels good on a dog's skin and can be a nice source of warmth on cooler days.

Though time spent in the sun is necessary for dogs, too much of it can have negative effects. In the hot summer months, excessive exposure to direct sunlight can lead to dehydration and heatstroke in dogs, both of which can be dangerous. It's unlikely that a couple of hours outdoors on a mild day will cause your pup any harm, but make sure to provide access to shade and plenty of water at all times.

Dogs who have very short or light-colored fur, hairless breeds (or dogs experiencing hair loss), and dogs with light-colored noses may be more sensitive to sun exposure. Too much time in the sun could lead to sunburn and even skin cancer for these dogs. If your pup falls into one of these categories, limit their sun exposure during the hottest parts of the year and look into getting dog-safe sunscreen for them.

Dogs love basking in the sun for the same reasons humans do. It feels good on their skin, warms them up, and helps regulate vitamin D and their hormone levels. It's a good idea to monitor how much time your dog spends in the sun on particularly hot days, but moderate amounts of sunshine are essential for a happy and healthy pup.